package com.alongthink.javademo.utilTools;

import lombok.extern.slf4j.Slf4j;

import java.io.*;
import java.nio.ByteBuffer;
import java.nio.MappedByteBuffer;
import java.nio.channels.FileChannel;

/**
 * @Auther: along
 * @Date: 2019/4/8 14:15
 * @Description: 文件读写
 */
@Slf4j
public abstract class FileUtils {
    /**
     * 写入文件
     * @param filePath 文件路径
     * @param content 待写入的文件内容
     */
    public static void write(String filePath, byte[] content) {
        FileChannel fc = null;
        try {
            File fileTemp = new File(filePath);
            File parent = fileTemp.getParentFile();
            if (!parent.exists()) parent.mkdirs();
            if (!fileTemp.exists()) fileTemp.createNewFile();

            RandomAccessFile acf = new RandomAccessFile(fileTemp, "rw");
            fc = acf.getChannel();
            MappedByteBuffer mbuf = fc.map(FileChannel.MapMode.READ_WRITE, 0, content.length);
            mbuf.put(content);
            fc.close();
        } catch (FileNotFoundException e) {
            log.info("写入文件失败,文件路径未找到,"+filePath);
        } catch (IOException e) {
            log.info("写入文件失败,"+e.getMessage());
        } finally {
            try {
                fc.close();
            } catch (IOException e) {
                log.info("关闭文件通道失败,"+e.getMessage());
            }
        }
    }

    /**
     * 写入文件
     * @param filePath
     * @param content
     */
    public static void write(String filePath, ByteBuffer content) {
        FileChannel fc = null;
        try {
            content.flip();
            File fileTemp = new File(filePath);
            File parent = fileTemp.getParentFile();
            if (!parent.exists()) parent.mkdirs();
            if (!fileTemp.exists()) fileTemp.createNewFile();

            RandomAccessFile acf = new RandomAccessFile(fileTemp, "rw");
            fc = acf.getChannel();
            MappedByteBuffer mbuf = fc.map(FileChannel.MapMode.READ_WRITE, 0, content.limit());
            mbuf.put(content);
            fc.close();
        } catch (FileNotFoundException e) {
            log.info("写入文件失败,文件路径未找到,"+filePath);
        } catch (IOException e) {
            log.info("写入文件失败,"+e.getMessage());
        } finally {
            try {
                fc.close();
            } catch (IOException e) {
                log.info("关闭文件通道失败,"+e.getMessage());
            }
        }
    }

    /**
     * 测试写入文件，文件大小=bs*1000*2000字节
     * @param file
     * @param bs
     */
    public static void write(File file,byte[] bs){
        try {
            long endTime2 = System.currentTimeMillis();
            RandomAccessFile acf = new RandomAccessFile(file, "rw");
            FileChannel fc = acf.getChannel();
            int len = bs.length * 1000;
            long offset = 0;
            int i = 2000000;
            while (i > 0) {
                MappedByteBuffer mbuf = fc.map(FileChannel.MapMode.READ_WRITE, offset, len);
                for (int j = 0; j < 1000; j++) {
                    mbuf.put(bs);
                }
                offset = offset + len;
                i = i - 1000;
            }
            fc.close();
            long endTime3 = System.currentTimeMillis();
            log.info("写入"+(bs.length*1000*2000/1024/1024/1024)+"G数据到文件用时："+(endTime3-endTime2)+"ms");
        }catch (FileNotFoundException e) {
//            e.printStackTrace();
            log.info("文件没有找到");
        } catch (IOException e) {
            e.printStackTrace();
        }
    }


    /**
     * 写入文件，该方法必须使用创建的FileChannel最为参数
     * RandomAccessFile acf = new RandomAccessFile(file, "rw");
     * FileChannel fc = acf.getChannel();
     * @param fc
     * @param bs 待写入文件的字节数组
     * @param offset 当前写入文件的偏移量
     */
    public static long write(FileChannel fc,byte[] bs,long offset){
        try {
            MappedByteBuffer mbuf = fc.map(FileChannel.MapMode.READ_WRITE, offset, bs.length);
            mbuf.put(bs);
            offset = offset + bs.length;
            return offset;
        } catch (IOException e) {
            log.info("写入文件异常"+e.getMessage());
        }
        return 0;
    }

    public static long write(FileChannel fc,ByteBuffer bbuf,long offset){
        try {
            int len = bbuf.limit();
            MappedByteBuffer mbuf = fc.map(FileChannel.MapMode.READ_WRITE, offset, len);
            mbuf.put(bbuf);
            offset = offset + len;
            return offset;
        } catch (IOException e) {
            log.info("写入文件异常"+e.getMessage());
        }
        return 0;
    }


    //========读取文件========================================================================
    /**
     * 以字节为单位读取文件，常用于读二进制文件，如图片、声音、影像等文件。
     */
    public static void readFileByBytes(String fileName,int readSize) {
        File file = new File(fileName);
        InputStream in = null;
        try {
            System.out.println("以字节为单位读取文件内容，一次读多个字节：");
            // 一次读多个字节
            byte[] tempbytes = new byte[readSize];
            int byteread = 0;
            in = new FileInputStream(fileName);
//            ReadFromFile.showAvailableBytes(in);
            // 读入多个字节到字节数组中，byteread为一次读入的字节数
            while ((byteread = in.read(tempbytes)) != -1) {
                System.out.write(tempbytes, 0, byteread);
            }
        } catch (Exception e1) {
            e1.printStackTrace();
        } finally {
            if (in != null) {
                try {
                    in.close();
                } catch (IOException e1) {
                }
            }
        }
    }

    /**
     * 以字符为单位读取文件，常用于读文本，数字等类型的文件
     */
    public static void readFileByChars(String fileName) {
        File file = new File(fileName);
        Reader reader = null;
        try {
            System.out.println("以字符为单位读取文件内容，一次读一个字节：");
            // 一次读一个字符
            reader = new InputStreamReader(new FileInputStream(file));
            int tempchar;
            while ((tempchar = reader.read()) != -1) {
                // 对于windows下，\r\n这两个字符在一起时，表示一个换行。
                // 但如果这两个字符分开显示时，会换两次行。
                // 因此，屏蔽掉\r，或者屏蔽\n。否则，将会多出很多空行。
                if (((char) tempchar) != '\r') {
                    System.out.print((char) tempchar);
                }
            }
            reader.close();
        } catch (Exception e) {
            e.printStackTrace();
        }
        try {
            System.out.println("以字符为单位读取文件内容，一次读多个字节：");
            // 一次读多个字符
            char[] tempchars = new char[30];
            int charread = 0;
            reader = new InputStreamReader(new FileInputStream(fileName));
            // 读入多个字符到字符数组中，charread为一次读取字符数
            while ((charread = reader.read(tempchars)) != -1) {
                // 同样屏蔽掉\r不显示
                if ((charread == tempchars.length)
                        && (tempchars[tempchars.length - 1] != '\r')) {
                    System.out.print(tempchars);
                } else {
                    for (int i = 0; i < charread; i++) {
                        if (tempchars[i] == '\r') {
                            continue;
                        } else {
                            System.out.print(tempchars[i]);
                        }
                    }
                }
            }

        } catch (Exception e1) {
            e1.printStackTrace();
        } finally {
            if (reader != null) {
                try {
                    reader.close();
                } catch (IOException e1) {
                }
            }
        }
    }

    /**
     * 以行为单位读取文件，常用于读面向行的格式化文件
     */
    public static void readFileByLines(String fileName) {
        File file = new File(fileName);
        BufferedReader reader = null;
        try {
            System.out.println("以行为单位读取文件内容，一次读一整行：");
            reader = new BufferedReader(new FileReader(file));
            String tempString = null;
            int line = 1;
            // 一次读入一行，直到读入null为文件结束
            while ((tempString = reader.readLine()) != null) {
                // 显示行号
                System.out.println("line " + line + ": " + tempString);
                line++;
            }
            reader.close();
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            if (reader != null) {
                try {
                    reader.close();
                } catch (IOException e1) {
                }
            }
        }
    }

    /**
     * 随机读取文件内容
     */
    public static void readFileByRandomAccess(String fileName) {
        RandomAccessFile randomFile = null;
        try {
            System.out.println("随机读取一段文件内容：");
            // 打开一个随机访问文件流，按只读方式
            randomFile = new RandomAccessFile(fileName, "r");
            // 文件长度，字节数
            long fileLength = randomFile.length();
            // 读文件的起始位置
            int beginIndex = (fileLength > 4) ? 4 : 0;
            // 将读文件的开始位置移到beginIndex位置。
            randomFile.seek(beginIndex);
            byte[] bytes = new byte[10];
            int byteread = 0;
            // 一次读10个字节，如果文件内容不足10个字节，则读剩下的字节。
            // 将一次读取的字节数赋给byteread
            while ((byteread = randomFile.read(bytes)) != -1) {
                System.out.write(bytes, 0, byteread);
            }
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            if (randomFile != null) {
                try {
                    randomFile.close();
                } catch (IOException e1) {
                }
            }
        }
    }

    /**
     * 读取文件，以字符串返回
     * @param file
     * @return
     */
    public static String readFile(File file) {
        try {
            InputStream in = null;
            StringBuffer sb = new StringBuffer();

            if (file.isFile() && file.exists()) { //判断文件是否存在
//            System.out.println("以字节为单位读取文件内容，一次读多个字节：");
                // 一次读多个字节
                byte[] tempbytes = new byte[1024];
                int byteread = 0;
                in = new FileInputStream(file);
                // 读入多个字节到字节数组中，byteread为一次读入的字节数
                while ((byteread = in.read(tempbytes)) != -1) {
                    //  System.out.write(tempbytes, 0, byteread);
                    String str = new String(tempbytes, 0, byteread);
                    sb.append(str);
                }
            } else {
//                logger.info("找不到指定的文件，请确认文件路径是否正确");
            }
            return sb.toString();
        } catch (FileNotFoundException e) {
            e.printStackTrace();
            return "";
        } catch (IOException e) {
            return "";
        }
    }

    /**
     * 显示输入流中还剩的字节数
     */
    private static int showAvailableBytes(InputStream in) {
        try {
            return in.available();
        } catch (IOException e) {
            return 0;
        }
    }

}
